The requested funds will be used to purchase a Zeiss LSM 510 laser scanning confocal microscope that will be the cornerstone instrument in a Life Sciences Imaging Facility at Northwestern University. Current imaging instruments at Northwestern are outdated and/or not capable of performing the types of imaging studies Northwestern researchers require. The new confocal microscope will be capable of high resolution, high sensitivity analysis of triple label fluorescence and 3-dimensional reconstruction from thick specimens. Items to be purchased are: a basic laser scanning confocal system with Argon and dual HeNe lasers, three photomultiplier tubes, transmitted light detection and an integrated computer system; an inverted microscope stand equipped for epifluorescence and differential interference contrast optics, Z-axis stage control; an anti-vibration table; and 3-dimensional reconstruction software. This confocal microscopy system represents a significant improvement over currently available imaging instrumentation at Northwestern. This new system will allow triple labeling studies and high resolution, 3-dimensional reconstruction of fine cellular process and subcellular compartments that are not possible with our current confocal microscope. This equipment will be used in a variety of developmental and cell biological studies, including: 1) "Estrogen-induced hippocampal seizure susceptibility," which involves imaging of neuronal axons and dendrites in rat hippocampus; 2) "Regulation of the Ci protein by signal transduction," which involves imaging Drosophila embryos and imaginal discs; 3) "Genetic control of cell fate diversity in Drosophila," which involves imaging Drosophila embryos and larvae; 4) "Control of olfactory and gustatory neuron regeneration," which involves imaging mouse embryos and explant cultures; 5) "Mechanism of activin action in granulosa cells" and "Inhibin actions on reproductive target cells," which involve imaging whole, unfixed mouse ovaries. All of these projects depend critically co-localization experiments in which it is essential to maximize resolution and color separation of individual fluorescent labels. Furthermore, many of these studies require the ability to assay the subcellular distribution of biomolecules and perform 3-dimensional reconstruction of labeled structures. These requirements necessitate a confocal microscope with the highest resolution, sensitivity and flexibility. Based upon technical considerations and demonstration of various confocal microscopy systems, we have determined that the Zeiss LSM 510 laser scanning confocal microscope is the best choice to meet the imaging needs of Life Science researchers at Northwestern University.